A factor analysis of 25 possible signs of minimal brain dysfunction defined factors representing school achievement (learning disabilities), hyperkinetic-impulse disorders social immaturity, and minor neurological problems (neurological soft signs). All children were given scores on each of the four factors. Children with symptoms in more than one area are more common than would be expected if there were no association among symptoms across the four areas, although most children who have problems in one area do not have problems in the other areas. Significant association of the factor scores have been found with socioeconomic, perinatal, and developmental variables; many antecedent variables are common to all MBD signs.